<p><b>Abstract</b>—This correspondence is originated by the definition of aspect given in a recent paper [<ref rid="bibi00571" type="bib">1</ref>] on the computation of aspect graphs of polyhedra. Simple examples are presented which show that the data stored according to this definition can be unsuitable for identifying an object or its attitude through a topological match. A definition is suggested which does not incur the problems pointed out.</p>